| | Key Biscayne, FL | Coral Gables, FL | United States |
| Population | 14,530 | 49,269 | 329,725,481 |
| Female Population | 51.3% | 53.8% | 50.5% |
| Male Population | 48.7% | 46.2% | 49.5% |
| Median Age | 41.7 | 39.9 | 38.4 |
| space3 | | | |
| Population - 2010 | 12,389 | 46,961 | 309,327,143 |
| Population - 2000 | 10,507 | 42,249 | 285,036,114 |
| Population - 1990 | 8,854 | 40,091 | 251,960,433 |
| Pop. 2000 to Now | 21.2% | 16.3% | 15.6% |
| Pop. 1990 to Now | 43.8% | 22.6% | 30.8% |
| space4 | | | |
| Population Density | 11,652.0 | 3,811.3 | 93.4 |
| Land Area | 1.2 | 12.9 | 3,531,905.4 |
| Water Area | 0.5 | 24.4 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Key Biscayne, FL | Coral Gables, FL | United States |
| Age 0 to 4 | 4.4% | 5.7% | 5.9% |
| Age 5 to 9 | 7.2% | 6.0% | 6.1% |
| Age 10 to 14 | 13.9% | 4.0% | 6.6% |
| Age 15 to 17 | 6.8% | 3.5% | 3.9% |
| Age 18 to 20 | 2.4% | 9.5% | 4.0% |
| Age 21 to 24 | 3.9% | 6.1% | 5.2% |
| Age 25 to 34 | 4.0% | 10.0% | 13.8% |
| Age 35 to 44 | 11.7% | 11.0% | 12.9% |
| Age 45 to 54 | 20.9% | 12.9% | 12.6% |
| Age 55 to 59 | 5.7% | 6.9% | 6.7% |
| Age 60 to 64 | 4.8% | 5.0% | 6.3% |
| Age 65 to 74 | 7.3% | 10.3% | 9.6% |
| Age 75 to 84 | 5.6% | 5.6% | 4.5% |
| Age 85 and over | 1.4% | 3.5% | 1.9% |
| space1 | | | |
| Race | | | |
| | Key Biscayne, FL | Coral Gables, FL | United States |
| White | 23.4% | 34.1% | 59.4% |
| Black | 0.3% | 3.4% | 12.2% |
| Asian | 0.2% | 3.1% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.1% | 0.0% | 0.2% |
| Other | 0.0% | 0.5% | 0.4% |
| Two or More Races | 1.6% | 1.8% | 3.2% |
| Hispanic | 74.3% | 57.1% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Key Biscayne, FL | Coral Gables, FL | United States |
| Married Population | 59.0% | 48.8% | 49.8% |
| Currently Married | 58.7% | 47.8% | 48.0% |
| Married but Separated | 0.3% | 1.0% | 1.8% |
| Single Population | 41.0% | 51.2% | 50.2% |
| Never Married | 29.0% | 36.1% | 33.8% |
| Divorced | 7.5% | 8.9% | 10.8% |
| Widowed | 4.5% | 6.3% | 5.6% |
| space5 | | | |
| Household Size | 3.17 | 2.38 | 2.60 |
| Households | 4,580 | 18,719 | 124,010,992 |
| Family Households | 3,584 | 11,524 | 80,755,759 |
| Married couple, w/children | 52.9% | 31.1% | 30.5% |
| Married couple, no children | 32.8% | 50.2% | 42.9% |
| Non Family Households | 996 | 7,195 | 43,255,233 |
| Single householder, w/children | 8.6% | 10.3% | 15.8% |
| Single householder, no children | 5.8% | 8.4% | 10.8% |